During an operation in which a flexible conduit is being laid in the sea, it is usually unwound from a surface ship which advances in conjunction with the laying, the conduit coming to rest on the bottom or being buried in it by a conduit burying apparatus moving along the bottom.
The conduit is stored on the ship on one or more storage means or devices, such as winches, reels, baskets, or containers, etc . . . from which it is unwound.
Applicant's Assignee Company has described in its French patent No. 79 08 774 a motorized winch apparatus on which can be placed the reels to unwind or wind up such conduits, particularly for conduit laying or raising.
During laying of conduit, or of course, raising, the tension or strain due to the weight of the conduit suspended from the conduit laying ship is normally taken up by various currently used means such as winches, motorized bearings or blocks, or linear traction devices, such as linear winches with grippers, and of course, caterpillar type pullers.
Clearing the edge of the ship, generally at the stern, can be achieved in various ways, for example, by causing the flexible tubular conduit to pass over a direction changing guide or deviator such as a fixed or movable channel or chute with or without rollers, or a grooved wheel.
In view of the evolution of current techniques at greater and greater depths, numerous problems occur.
The increase in depth of water and/or the use of conduits of significant weight lead to greater and greater forces which can damage the conduit when it flexes, especially while it is passing over the direction changing means in the form of a channel or grooved wheel used to clear the side of the ship. On the other hand, the conduit always has along its length rigid exterior accessories with a diameter greater than that of the conduit and which constitute singular points or spaced apart locations which, when they pass over the direction changing means, embed themselves more or less in this latter and cause in the conduit constraints of flexion under traction, which cannot be absorbed without damage to the conduit.
Among the different such points which could be encountered can be cited the connectors located at the ends of the conduits or in the running portions for the connection of successive sections, and anodes, manouevering rings, devices for limiting curvature, stiffeners, etc . . .
To attempt to overcome these disadvantages, it has already been proposed, when the traction on the conduit is not too great, that there be placed, especially to help the intermediate connectors clear the direction changing means, a shoe or "sock" located on the conduit, below the connector, and put in tension by retention means such as slings operated by a winch on the deck of the ship. Thus, the connector is flexed without traction on the direction changing means. Such a technique quickly becomes unacceptable with increasing tension stresses in the conduit as a result of the insufficient hold of the shoe or sock and risk of damage to the outer coating or sheath of the conduit.
To attempt to resolve this problem, it has been proposed that there be mounted concentrically around the flexible conduit, articulated rings with a diameter equal to the outer diameter of the accessory constituting the singular point, the radius of the rings decreasing progressively on each side of the accessory toward the diameter of the flexible conduit.
Such a solution leads to obstructions and high costs, and, moreover, cannot be used when the radius of the wheel or the channel constituting the direction changing means is close to the minimum radius of curvature of the flexible conduit.